Stubborn ID3 Tags

I have been rearranging my music collection and I have come across several files that will not let me change their ID3 Tags. The files are not read-only and neither is their parent folder. They are not flagged as copyrighted and I can view the previous ID3 information easily. I have tried to change the tags in both Winamp and TagScanner but neither will do it. Any ideas why this might be or what I could do about it short of transcoding it?

I think I may have figured it out. The files in question have APEv2 set as their primary tag which is conflicting with one of the other tags written (ID3v1 I think). I set ID3v2 as the primary tag and it took care of everything.